Abb Schweiz Ag

Abb Power Grids Switzerland Ag

Lin Yang

Klaus Bohnert

Andreas Frank

Xun Gu

Georg Müller

Georg Muller

In order to carry out the polarimetric detection of a measurand, light of two polarization states is passed through a sensing element, where the two states suffer a differential phase shift depending on the value of the measurand. In order to compensate for only imperfections of the device, a method is proposed that is based on calibration values obtained in a low-value regime of the measurand only. Yet the method can still be used for accurately determining higher values of the measurand.

Polarization optical detection with enhanced accuracy in the high-signal regime

There is described an optical fiber current sensor having an opto-electronic module part for detecting an optical phase shift induced by the measurand field in a sensing fiber, a sensor head including the sensing fiber, wherein the sensing fiber is a spun highly-birefringent fiber having a length L=&#x222b; ds defined by the line integral along the space curve given by the sensing fiber coil such that the length L of the sensing fiber is sufficiently long to suppress thermal signal instabilities due to the spun character of the sensing fiber while the effective number of fiber windings is low enough to maintain a maximum sensitivity over the full measurement range of the fiber-optical sensor.

Optical sensor with spun birefringent sensing fiber

A method of increasing accuracy of optical sensors based on generating two sets of light waves having different velocities in the presence of a non-vanishing measurand field within a sensing element of the sensor is described. A defined static bias phase shift is introduced between the two sets of light waves. The sensor converts a total optical phase shift including static bias optical phase shifts and measurand-induced optical phase shifts into anti-phase optical power changes in at least two detector channels. The method includes steps of normalizing the optical power changes after their conversion into electrical detector signals in the two detector channels to reduce effects of uneven intensity or power of the light source and different loss or gain in the detector channels. Further methods, sensors and apparatus for temperature stabilizing such optical sensors and novel sensors are also presented.

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Widen, Switzerland

Lin Yang